JP2023076887A - Interference filter, spectroscopic measuring device, and spectroscopic measuring system - Google Patents

Abstract

To provide an interference filter capable of emitting light of high optical intensity, and a spectroscopic measuring device equipped with the interference filter, and a spectroscopic measuring system equipped with the spectroscopic measuring device.SOLUTION: The interference filter includes a first and a second optical region facing each other via a gap, and a distance change part for changing the distance between the first and the second optical regions. The first optical region includes a first passage part that passes light through and a first reflection part that reflects light, and the second optical region includes a second passage part that passes light through and a second reflection part that reflects light. Some of the incident light entered from the light incidence side passes through the first passage part and is reflected by the second and the first reflection parts in order, thus becoming reflected-component light that passes through the second passage part. The other of the incident light passes through the first passage part and becomes passed-component light without being reflected by the second and first reflection parts, with the reflected-component light and the passed-component light emitted to the light emission side.SELECTED DRAWING: Figure 2

Description

The present invention relates to interference filters, spectroscopic measurement devices, and spectroscopic measurement systems.

2. Description of the Related Art Conventionally, an interference filter that disperses light of a predetermined wavelength from incident light is known (for example, Patent Document 1).
For example, the interference filter described in Patent Document 1 is a so-called Fabry-Perot etalon, has a first reflective film and a second reflective film facing each other across a gap, and uses an electrostatic actuator to move the first reflective film and the second reflective film. The distance between the second reflective films can be changed.
In such an interference filter, light is multiple-reflected between the first reflective film and the second reflective film, and the peak wavelength is a predetermined wavelength that is strengthened by interference. Light in a wavelength range with a predetermined half-value width corresponding to the bending state or the like is transmitted.

JP 2019-61283 A

However, in the interference filter as described in Patent Document 1, light centered on a peak wavelength corresponding to the distance between the first reflecting film and the second reflecting film is transmitted, but light of other wavelengths is transmitted from the light incident side. reflected to
Therefore, when the light that has passed through such an interference filter is detected by a photodetector such as an image pickup device, there is a problem that the amount of detected light decreases. In addition, although a reflective film used in an interference filter as described in Patent Document 1 transmits part of incident light, the rest is reflected, absorbed, and scattered by the reflective film, resulting in loss of that amount of light. As a result, the amount of light detected by the photodetector is further reduced.

The interference filter according to the first aspect of the present disclosure includes a first optical region and a second optical region facing each other across a gap, and a distance changer that changes the distance between the first optical region and the second optical region wherein the first optical region includes a first passing portion that transmits light and a first reflecting portion that reflects light, and the second optical region includes a second passing portion that transmits light and a second reflecting portion for reflecting light, the side opposite to the second optical region of the first optical region is the light incident side, and the side opposite to the first optical region of the second optical region is the light emission side, part of the incident light that enters from the light incidence side passes through the first passing section, is reflected in order by the second reflecting section and the first reflecting section, and The reflected component light passes through the second passing section, and the other portion passes through the first passing section and passes through the second passing section without being reflected by the second reflecting section and the first reflecting section. The reflected component light and the passing component light are emitted to the light emitting side.

The interference filter of the first aspect comprises a first substrate having the first optical region and a second substrate having the second optical region, wherein the first optical region is the second optical region of the first substrate. provided on a surface facing the substrate and having a plurality of first holes forming the first passing portion, and a portion other than the first hole portions being constituted by a first mirror forming the first reflecting portion; , the second optical region is provided on a surface of the second substrate facing the first substrate, has a plurality of second holes constituting the second passing portion, and has a plurality of second holes other than the second holes A portion is composed of a second mirror that constitutes the second reflecting portion.

In the interference filter of the first aspect, when the first optical region is projected onto the second optical region in the direction in which the incident light travels, the first passing section includes a part of the second passing section and the It overlaps a portion of the second reflecting portion, and the second passing portion overlaps a portion of the first passing portion and a portion of the first reflecting portion.

A spectroscopic measurement device according to a second aspect of the present disclosure includes the interference filter according to the first aspect described above, and a light detection section that detects light emitted from the light emission side of the interference filter.

The spectroscopic measurement device of the second aspect further includes an angle adjustment section that changes the installation angle of the interference filter with respect to the optical axis of the light detection section.

A spectroscopic measurement system according to a third aspect of the present disclosure includes a spectroscopic measurement device according to the second aspect, and based on a signal value output from the photodetector, the light intensity of light of each wavelength included in the incident light is determined. a calculating processor, wherein the processor calculates the light intensity of the light of each wavelength from the change in the signal value when the gap is changed by Fourier analysis.

1 is a schematic diagram showing a spectroscopic measurement system according to a first embodiment; FIG. 4A and 4B are diagrams showing a schematic configuration of an interference filter according to the first embodiment and a positional relationship between the interference filter and a photodetector; FIG. The schematic plan view which shows an example of the 1st mirror of 1st embodiment. 4 is a flowchart showing a spectroscopic measurement method in the spectroscopic measurement system of the first embodiment; FIG. 4 is a diagram showing an example of measurement results for a measurement target and light intensity of each wavelength obtained by Fourier analysis; FIG. 7 is a diagram showing a schematic configuration of an interference filter according to a second embodiment and a positional relationship between the interference filter and a photodetector; FIG. 8 is a plan view showing the configuration of a first mirror according to Modification 1; FIG. 10 is a diagram showing the positional relationship between an interference filter and a photodetector according to Modification 2; 8A and 8B are diagrams showing a schematic configuration of an interference filter according to Modification 2 and a positional relationship between the interference filter and a photodetector; FIG.

[First embodiment]
A first embodiment will be described below.
FIG. 1 is a schematic diagram showing the spectroscopic measurement system of this embodiment.
A spectroscopic measurement system 1 of the present embodiment includes a spectroscopic measurement device 10 and a control device 20 that controls the spectroscopic measurement device 10, as shown in FIG.

[Configuration of spectrometer 10]
The spectrometer 10 is a device that analyzes the light intensity of each wavelength of the light reflected by or transmitted through the measurement object W and measures the spectrum. In this embodiment, an example of measuring the light to be measured that is reflected by the object to be measured W is shown. It may be used as target light. Also, as the spectroscopic measurement device 10, a device that measures a spectroscopic spectrum is exemplified, but the spectroscopic measurement device 10 may function as a spectroscopic camera.

As shown in FIG. 1, the spectrometer 10 includes an optical system 11 that guides light reflected by the object W to be measured, an interference filter 100, a photodetector 12, and a module controller 13. ing.

[Configuration of interference filter 100]
FIG. 2 is a diagram showing the schematic configuration of the interference filter 100 of this embodiment and the positional relationship between the interference filter 100 and the photodetector 12. As shown in FIG.
The interference filter 100 of this embodiment comprises a first substrate 110 and a second substrate 120 . The first substrate 110 and the second substrate 120 are translucent substrates. For example, when performing spectroscopic measurement in the visible light region with the spectrometer 10, soda glass, crystalline glass, quartz glass, etc. can be used. Silicon or the like may be used when performing spectrometry in the near-infrared region or the infrared region. That is, the first substrate 110 and the second substrate 120 are formed of substrates that can transmit light in the wavelength range to be measured in the spectroscopic measurement performed by the spectroscopic measurement device 10 .
A first optical region 130 is provided on the surface of the first substrate 110 facing the second substrate 120, and a second optical region 140 is provided on the surface of the second substrate 120 facing the first substrate 110. It is The first optical region 130 and the second optical region 140 are arranged facing each other with a gap G therebetween. The interference filter 100 is also provided with an electrostatic actuator 150 (distance changing section) that changes the distance between the first optical region 130 and the second optical region 140 .
The interference filter 100 will be described in detail below.
In the following description, the substrate thickness direction of the first substrate 110 and the second substrate 120 is defined as the Z direction, and a planar view from the Z direction is referred to as a filter planar view. Further, in this embodiment, the center point of the first optical region 130 and the center point of the second optical region 140 are assumed to coincide with each other in the plan view of the filter. _LF .

[Configuration of first substrate 110].
The first substrate 110 includes, as shown in FIG. 2, an electrode placement groove 111 formed by etching or the like, and a mirror installation portion 112 .
The electrode arrangement groove 111 is, for example, a substantially annular concave groove formed in the center of the first substrate 110, in which the first electrode 151 constituting the electrostatic actuator 150 is arranged. The first electrode 151 may be directly provided on the bottom surface of the electrode placement groove 111, or may be provided on the bottom surface of the groove by providing another thin film layer.

The first electrode 151 is, for example, formed in a substantially annular shape, preferably in an annular shape. Note that the term "substantially annular" as used herein also includes a shape having a notch in part, such as a C-shape. In addition, in the present embodiment, an example in which one first electrode 151 is provided is shown. and so on.
A lead electrode (not shown) is connected to the first electrode 151, and the first electrode 151 is connected to the module controller 13 (see FIG. 1) via the lead electrode.

The mirror installation portion 112 is arranged in the center of the electrode arrangement groove 111 in the filter plan view, and is formed to protrude toward the second substrate 120 side, for example. A first mirror 131 forming a first optical region 130 is provided on the projecting tip surface of the mirror installation portion 112 .

In this embodiment, the configuration in which the mirror installation portion 112 protrudes toward the second substrate 120 from the bottom surface of the electrode arrangement groove 111 is exemplified, but the present invention is not limited to this. For example, even if the mirror installation portion 112 is formed in a concave shape, the bottom surface of the mirror installation portion 112 is positioned further from the second substrate 120 than the groove bottom surface of the electrode arrangement groove 111, and the first mirror 131 is provided on the bottom surface. good. Alternatively, the mirror mounting portion 112 may be flush with the groove bottom surface of the electrode arrangement groove 111 .

FIG. 3 is a plan view showing an example of the first mirror 131. As shown in FIG.
As shown in FIG. 3, the first mirror 131 is provided with a plurality of first holes 131A in plan view in the Z direction. In this embodiment, these first hole portions 131A constitute first passage portions that allow light to pass therethrough. Moreover, in the first mirror 131, the portion other than the first hole portion 131A becomes the first reflecting portion 131B that reflects light.
In the present embodiment, as shown in FIG. 3, the first hole portion 131A is formed in a slit shape having a longitudinal direction in the Y direction perpendicular to the Z direction, and the first reflecting portion surrounds the first hole portion 131A. 131B is provided.

The first mirror 131 may be directly provided on the mirror installation portion 112, or may be provided on the mirror installation portion 112 by providing another translucent thin film (layer) thereon.
Moreover, a semi-transmissive film material that transmits a part of incident light and reflects a part of the incident light is usually used for the reflective film used in the Fabry-Perot etalon. In contrast, in the present embodiment, a reflecting film that totally reflects incident light can be used as the first mirror 131 . The material of the first mirror 131 is not particularly limited, and for example, a metal film such as Ag or a conductive alloy film such as Ag alloy can be used. When using a metal film such as Ag, a protective film may be formed in order to suppress deterioration of Ag.
Alternatively, for example, a dielectric multilayer film may be used in which the high refractive index layer is TiO ₂ and the low refractive index layer is SiO ₂ , and the high refractive index layer and the low refractive index layer are alternately laminated. A reflective film obtained by laminating a dielectric multilayer film and a metal film, a reflective film obtained by laminating a dielectric single-layer film and an alloy film, or the like may be used.

The first optical region 130 faces the second optical region 140 provided on the second substrate 120 with a gap G therebetween.
Here, in this embodiment, an example in which the gap G between the mirrors 131 and 141 is smaller than the gap between the first electrode 151 and the second electrode 152 that constitute the electrostatic actuator 150 is shown, but the present invention is not limited to this. For example, when infrared rays or far infrared rays are used as the light to be measured, the gap G may be larger than the gap between the electrodes 151 and 152 depending on the wavelength range of the light to be measured. In this case, as described above, the mirror mounting portion 112 of the first substrate 110 is formed in a concave shape.

The surface of the first substrate 110 on which recesses such as the electrode arrangement groove 111 and the mirror installation portion 112 are not provided is bonded to the second substrate 120 via a bonding film (not shown).

[Configuration of Second Substrate 120]
The second substrate 120 includes, as shown in _FIG. and a substrate outer peripheral portion 123 provided on the substrate.

The movable portion 121 is formed to be thicker than the diaphragm portion 122. For example, in this embodiment, the movable portion 121 is formed to have the same dimension as the thickness of the second substrate 120 (substrate peripheral portion 123). A second optical region 140 facing the first optical region 130 is provided on the surface of the movable portion 121 facing the first substrate 110 . Specifically, the second optical region 140 is composed of a second mirror 141 . The second mirror 141 may be directly provided on the movable portion 121, or may be provided on another thin film (layer).

The second mirror 141 is provided at the center of the movable portion 121 so as to face the first mirror 131 with a gap G therebetween. As the second mirror 141, a reflective film having substantially the same configuration as that of the first mirror 131 described above is used. In other words, like the first mirror 131, the second mirror 141 may be formed of a film material or film thickness that totally reflects incident light. A multilayer film or the like can be used.
3, the second mirror 141 is provided with a plurality of second holes 141A that are slit-shaped in the Y direction when viewed from above in the Z direction. In terms of form, this second hole 141A constitutes a second passage through which light passes. In the second mirror 141, the portion other than the second hole portion 141A serves as a second reflection portion 141B that reflects light. It is

Here, in the present embodiment, as shown in FIG. 2, when the second mirror 141 is projected onto the first optical region 130 along the Z direction, the second hole portion 141A overlaps the first reflecting portion 131B, The second mirror 141 is arranged such that the second reflecting portion 141B overlaps the first hole portion 131A.

The diaphragm portion 122 is a diaphragm that surrounds the movable portion 121 and connects the substrate outer peripheral portion 123 and the movable portion 121 , and is formed to have a smaller thickness than the movable portion 121 . Such a diaphragm part 122 is more flexible than the movable part 121, and can displace the movable part 121 toward the first substrate 110 with a slight stress. At this time, since the movable portion 121 has a larger thickness dimension and a higher rigidity than the diaphragm portion 122, even when the movable portion 121 is pulled toward the first substrate 110, the shape change of the movable portion 121 can be suppressed.
In this embodiment, the diaphragm-shaped diaphragm part 122 is exemplified, but it _is not limited to this. It is good also as the structure etc. which a part is provided.

Like the first electrode 151, the second electrode 152 is formed in a substantially annular shape, preferably in a substantially annular shape around the filter center axis _LF . Further, the second electrode 152 may be configured in a shape in which a part of the ring is notched, such as a C shape, for example, similarly to the first electrode 151, and is configured by a plurality of annular electrodes. good too.
In the present embodiment, an example in which the second electrode 152 is provided on the diaphragm portion 122 is shown, but the present invention is not limited to this. A configuration in which the second electrode 152 is provided from 121 to the diaphragm portion 122 may be adopted.

An extraction electrode (not shown) is connected to the second electrode 152, and the second electrode 152 is connected to the module control unit 13 (see FIG. 1) via the extraction electrode.

The board|substrate outer peripheral part 123 is a part provided outside the diaphragm part 122 in filter planar view. The substrate peripheral portion 123 is bonded to the first substrate 110 via a bonding layer (not shown).

[Another configuration of the spectrometer 10]
Next, another configuration of the spectrometer 10 will be described.
The optical system 11 includes a plurality of lenses, a diaphragm, and the like that guide light reflected or transmitted by the object W to be measured to the interference filter 100 and the light detection section 12 . The optical system 11 may include, for example, an incident lens for receiving incident light, a collimator lens for collimating the incident light, and a condenser lens for condensing light to the photodetector 12 . When the spectroscopic measurement device 10 functions as a spectroscopic camera, an image sensor is used as the light detection unit 12. In this case, the optical system includes an imaging lens that forms an image of image light on the image sensor and a telecentric optical system. may be included.

The photodetector 12 receives light and outputs a signal corresponding to the intensity of the received light. A CCD (Charge-Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, or the like can be used as the light detection unit 12 . As described above, the photodetector 12 may be an image sensor that has a plurality of pixels and outputs a signal for each pixel.

The module control section 13 is a control circuit that is connected to the interference filter 100 and the light detection section 12 and controls the operation of the spectroscopic measurement device 10 . Specifically, the module control section 13 controls the drive voltage applied to the electrostatic actuator 150 of the interference filter 100 . The module control unit 13 also receives a light reception signal output from the light detection unit 12 and transmits the light reception signal to the control device 20 .

[Position of interference filter with respect to photodetector]
Next, the positional relationship between the interference filter 100 and the photodetector 12 in this embodiment will be described.
In this embodiment, as shown in FIG. 2, the interference filter 100 is arranged such that the filter central axis _LF is inclined with respect to the optical axis _LD of the photodetector 12 . In this embodiment, as described above, the first hole portion 131A of the first mirror 131 and the second reflecting portion 141B of the second mirror 141 overlap with each other in the filter plan view, and the first reflecting portion 131B of the first mirror 131 overlaps. and the second hole 141A of the second mirror 141 overlap.
Therefore, the filter central axis _LF is inclined with respect to the optical axis _LD of the photodetector 12, and out of the light that has entered the interference filter 100 along the optical axis _LD , it enters the first hole 131A. A part of the emitted light passes through the second hole 141A and goes to the photodetector 12 as it is. This light component becomes the transmitted component light of the present disclosure.
On the other hand, the remaining part of the light incident on the first hole portion 131A of the interference filter 100 along the optical axis _LD is reflected by the second reflecting portion 141B, then reflected by the first reflecting portion 131B, It passes through the second hole 141A and goes to the photodetector 12 . The light component becomes the reflected component light of the present disclosure.
That is, in the present embodiment, the X-direction width (slit width) of the first hole portion 131A and the second hole portion 141A, and the first reflecting portion 131B are , the width of the second reflecting portion 141B in the X direction, and the angle of the filter center axis _LF with respect to the optical axis _LD .

In this embodiment, interference light between the transmitted component light and the reflected component light is output from the interference filter 100 . The optical path length difference l between the transmitted component light and the reflected component light is the distance _lG of the gap G corresponding to the driving voltage applied to the electrostatic actuator 150, and the inclination angle θ of the filter center axis _LF with respect to the optical axis _LD . and l=2l _G /cos θ. Then, due to the optical path length difference l, the wavelength of the constructive light changes due to interference. That is, light beams having a wavelength λ satisfying l=nλ (where n is a natural number) are output from the interference filter 100 after constructive interference.
In this embodiment, the driving voltage to the electrostatic actuator 150 can change the distance _lG of the gap G, thereby changing the wavelength λ of the light constructive by interference.

In addition, in this embodiment, the first mirror 131 and the second mirror 141 are shown as examples that do not have light transmittance. That is, the light incident on the first reflecting portion 131B of the first optical region 130 from the first substrate 110 side is reflected toward the first substrate 110 side and does not pass through the gap G. FIG.

[Configuration of control device 20]
The control device 20 analyzes the spectrum of the measurement object W based on the measurement results of the spectrometer 10 .
The control device 20 can be configured by a general computer such as a personal computer, a smartphone, a tablet terminal, etc., and as shown in FIG. It is
The storage unit 21 stores various data related to spectroscopic measurement performed by the spectroscopic measurement system 1 and various programs.
Various data include, for example, a voltage table for driving the electrostatic actuator 150 of the interference filter 100 . As the voltage table, for example, the relationship between the distance _lG of the gap G and the drive voltage applied to the electrostatic actuator 150 is stored. Instead of the distance _lG of the gap G, the optical path length difference l between the transmitted component light and the reflected component light may be recorded.

The processor 22 implements various functions by reading and executing programs stored in the storage unit 21. For example, in the present embodiment, as shown in FIG. do.

The measurement command unit 221 controls the spectrometer 10 to perform measurement on the measurement target W, and the light detection unit for each distance _lG when the distance _lG of the gap G in the interference filter 100 is sequentially changed. A signal value of the received light signal from 12 is acquired as a measurement result.

As described above, the distance _lG varies depending on the drive voltage applied to the electrostatic actuator 150, and the distance _lG corresponds to the drive voltage on a one-to-one basis. In addition, the variation of the distance _lG varies the optical path length difference l between the transmitted component light and the reflected component light, thereby varying the center wavelength of the light constructive by interference. Therefore, instead of the signal value of the light receiving signal for each distance _lG , the signal value of the light receiving signal for the driving voltage applied to the electrostatic actuator 150 may be obtained as a measurement result, and the signal of the light receiving signal for the optical path length difference l may be obtained. A value may be obtained as a measurement result.

The analysis unit 222 analyzes the obtained measurement result and performs spectrometry on the measurement object W. FIG. For example, in the present embodiment, the analysis unit 222 calculates the light intensity of each wavelength included in the incident light from the measurement object W by analyzing the measurement result using Fourier analysis. Calculate

[Spectroscopic measurement method of spectroscopic measurement system 1]
Next, the spectroscopic measurement method of the spectroscopic measurement system 1 as described above will be described.
FIG. 4 is a flowchart showing a spectroscopic measurement method in the spectroscopic measurement system 1 of this embodiment.
In the spectroscopic measurement system 1 of the present embodiment, when spectroscopically measuring the object W to be measured, first, the object W to be measured is measured using the spectroscopic measurement device 10 (step S1).
For example, the measurement command unit 221 of the control device 20 sequentially changes the gap G of the interference filter 100 to a plurality of preset distances l _G (a plurality of optical path length differences l). Measure the amount of light received. In this case, the measurement command unit 221 reads the driving voltage to be applied to the electrostatic actuator corresponding to each distance l _G (each optical path length difference l) from the voltage table in the storage unit 21 and outputs it to the spectrometer 10 . Accordingly, the spectrometer 10 sequentially switches the driving voltage applied to the electrostatic actuator 150 of the interference filter 100 to measure the received light signal output from the photodetector 12 .
Then, the spectrometer 10 outputs the signal value of each light receiving signal when the gap G is set to each distance _lG to the control device 20 as a measurement result.

When the measurement command unit 221 acquires the measurement result from the spectrometer 10, the analysis unit 222 performs Fourier analysis on the measurement result to calculate the light intensity for each wavelength (step S2).
FIG. 5 is a diagram showing an example of the measurement results for the object W to be measured and the light intensity of each wavelength obtained by Fourier analysis.
In FIG. 5, the solid line shows the change in signal strength of the received signal when the optical path length difference is changed from 100 nm to 2500 nm. The dashed line indicates the signal intensity of only the light component with a wavelength of 400 nm in the light received by the photodetector 12, and the dashed line indicates the signal intensity of only the light component with a wavelength of 700 nm in the light received by the photodetector 12. Indicates signal strength.
The measurement command unit 221 acquires the measurement result indicated by the solid line in FIG. 5, for example. Then, the analysis unit 222 performs Fourier analysis on the measurement results to analyze a plurality of waveforms included in the measurement results indicated by dashed lines and dashed lines in FIG. Analyze intensity and To simplify the explanation, the example shown in FIG. 5 is an example in which two wavelength components with the same signal intensity are analyzed. are analyzed, and the signal intensity for each wavelength component is calculated.

[Action and effect of the present embodiment]
The interference filter 100 of this embodiment includes a first optical region 130 and a second optical region 140 that face each other across a gap G, and a distance changing filter that changes the distance between the first optical region 130 and the second optical region 140 . and an electrostatic actuator 150 as a unit. The first optical region 130 includes a first hole portion 131A of the first mirror 131, which is a first passing portion for transmitting light, and a first reflecting portion 131B of the first mirror 131 for reflecting light. . Also, the second optical region 140 includes a second hole portion 141A of the second mirror 141 as a second passing portion for passing light, and a second reflecting portion 141B of the second mirror 141 for reflecting light. be done. Part of the incident light that enters from the opposite side of the first substrate 110 to the second substrate 120 passes through the first hole 131A and is reflected in order by the second reflecting portion 141B and the first reflecting portion 131B. It becomes the reflected component light that passes through the second hole 141A. Another part of the incident light passes through the first hole portion 131A and becomes passing component light that passes through the second hole portion 141A without being reflected by the second reflecting portions 141B and 131B. . In this embodiment, interference light between the reflected component light and the transmitted component light is emitted from the second substrate side.

In such an interference filter 100, light emitted from the interference filter 100 includes passing component light that passes through the first reflecting section 131B and the second reflecting section 141B without being reflected. Passing component light is not diffused or absorbed by the reflecting portions 131B and 141B. Therefore, in the interference filter 100 of this embodiment, the light intensity of emitted light can be increased compared to, for example, a Fabry-Perot etalon. As a result, when spectroscopic measurement is performed based on the light emitted from the interference filter 100, spectroscopic measurement can be performed while suppressing the influence of noise.

The interference filter 100 of this embodiment comprises a first substrate 110 having a first optical region 130 and a second substrate 120 having a second optical region 140 . A plurality of first holes 131A are provided on the surface of the first substrate 110 facing the second substrate 120 and constitute the first passing portion. A first optical region 130 is configured by the first mirror 131, which is 131B. Further, the surface of the second substrate 120 facing the first substrate 110 has a plurality of second hole portions 141A that constitute the second passing portion, and the portions other than the second hole portions 141A are the second reflecting portions. A second optical region 140 is configured by the second mirror 141, which is 141B.

In such a configuration, a first mirror 131 having a plurality of first holes 131A is provided on the first substrate 110, and a second mirror 141 having a plurality of second holes 141A is provided on the second substrate 120. , the interference filter 100 that emits the interference light between the passing component light and the reflected component light can be easily configured, and the configuration can be simplified.

In the interference filter 100 of the present embodiment, when the first optical region 130 is projected onto the second optical region 140 along the traveling direction of incident light, that is, along the optical axis _LD of the photodetector 12, the first aperture 131A overlaps a portion of the second hole portion 141A and a portion of the second reflecting portion 141B, and the second hole portion 141A overlaps a portion of the first hole portion 131A and a portion of the first reflecting portion 131B.
As a result, by allowing incident light to enter the interference filter 100 along the optical axis _LD , each of the second holes in the region where the first optical region and the second optical region overlap with respect to the direction of travel of the optical axis. Interference light between the transmitted component light and the reflected component light can be emitted from 141A.

The spectroscopic measurement apparatus 10 of this embodiment includes the above-described interference filter 100 and a light detection section 12 that detects light emitted from the light emission side of the interference filter 100 .
As described above, the interference filter 100 can increase the intensity of emitted light compared to, for example, a Fabry-Perot etalon. Therefore, in the spectrometer 10 using the interference filter 100, when the light detection section 12 detects the light emitted from the interference filter 100, the amount of light received by the light detection section 12 can be increased. Therefore, the spectroscopic measurement apparatus 10 of the present embodiment can perform spectroscopic measurement with high accuracy while suppressing the influence of noise.

The spectroscopic measurement system 1 of this embodiment includes the spectroscopic measurement device 10 and the control device 20 as described above. The control device 20 includes one or more processors 22. The processors 22 acquire signal values output from the photodetector 12 of the spectrometer 10 when the interference filter 100 is changed, and perform Fourier The signal value is analyzed by analysis, and the light intensity of light of each wavelength included in the incident light is calculated.
Generally, in conventional spectroscopic measurement using a spectroscopic element such as a Fabry-Perot etalon, light having a predetermined half-value width centered on a specific peak wavelength and corresponding to the performance of the spectroscopic element is transmitted through the spectroscopic element. In this case, by improving the performance of the spectroscopic element and narrowing the half width, it is possible to accurately measure the light intensity of the light of the peak wavelength. However, when the half-value width is narrowed, the intensity of light transmitted through the spectroscopic element is correspondingly reduced, increasing the influence of noise. On the other hand, in the present embodiment, as described above, both the transmitted component light and the reflected component light are received by the photodetector 12. Therefore, like the Fabry-Perot etalon, the peak center is the specific wavelength. Therefore, the signal value output from the photodetector 12 can be increased, and the influence of noise can be suppressed.
Further, in this embodiment, as described above, light of a specific wavelength is not transmitted, but Fourier analysis is performed from the light intensity change (signal value change) of the interference light when the optical path difference l is changed. to calculate the light intensity for each wavelength. Therefore, unlike a spectroscopic element that transmits light having a predetermined half-value width centered on a specific peak wavelength, the performance of the interference filter 100 does not reduce the measurement accuracy, and the measurement accuracy can be improved. In other words, in the spectroscopic measurement system 1 of the present embodiment, highly accurate spectroscopic measurement can be performed while suppressing the influence of noise.

[Second embodiment]
Next, a second embodiment will be described.
In the above-described first embodiment, an example in which the interference filter 100 is arranged such that the filter central axis _LF is inclined with respect to the optical axis _LD of the photodetector 12 is shown.
In contrast, the second embodiment differs from the first embodiment in that the arrangement angle of the interference filter 100 can be adjusted. In the following description, the same reference numerals are given to the configurations already described, and the description thereof will be omitted or simplified.

FIG. 6 is a diagram showing a schematic configuration of the spectroscopic measurement device 10A of this embodiment.
The spectroscopic measurement system of this embodiment includes a spectroscopic measurement device 10A and a control device 20, as in the first embodiment. Here, the spectroscopic measurement apparatus 10A of this embodiment includes an optical system 11, an interference filter 100, a light detection section 12, and a module control section 13, as well as an angle adjustment section 14, as shown in FIG.

The angle adjuster 14 is connected to the interference filter 100 and adjusts the installation angle of the interference filter 100 , that is, the angle of the filter central axis _LF with respect to the optical axis _LD of the photodetector 12 . The specific configuration of the angle adjusting section 14 is not particularly limited. For example, as shown in FIG _. Equipped with a rotary drive shaft 14B perpendicular to the filter central axis _LF , and a drive unit (not shown) (motor, piezoelectric actuator, etc.) for rotating the holder 14A holding the interference filter 100 around the rotary drive shaft 14B. Configuration and the like can be exemplified. 6 shows an example in which the rotation drive shaft 14B for rotating the interference filter 100 in the angle adjustment unit 14 is provided on one end side of the interference filter 100. For example, the filter center axis L of the interference filter 100 One point on _F may be the center of rotation.

In this embodiment, the amount of rotation of the interference filter 100 by the angle adjusting section 14 (signal value for driving the driving section) is recorded in the storage section 21 of the control device 20 as a voltage table. That is, in the present embodiment, for example, the drive voltage applied to the electrostatic actuator 150 and the amount of rotation of the interference filter 100 with respect to the distance _lG of the gap G are recorded as the voltage table. As the amount of rotation of the interference filter 100, for example, it is preferable to record the amount of rotation that makes the light amount of the passing component light constant even when the distance _lG of the gap G changes.
Note that instead of the distance l _G of the gap G, the optical path difference l between the transmitted component light and the reflected component light may be recorded, and the wavelength λ of the light that is strengthened by interference is recorded at the optical path difference l. may have been

Then, when the measurement command unit 221 controls the spectrometer 10 to perform measurement on the object W to be measured, the measurement command unit 221 corresponds to each distance l _G (each optical path length difference l) from the voltage table in the storage unit 21. The driving voltage applied to the electrostatic actuator and the amount of rotation in the angle adjusting section 14 are read out and output to the spectroscopic measurement device 10 .
In such a spectroscopic measurement system, the spectroscopic measurement apparatus 10A sequentially switches the driving voltage applied to the electrostatic actuator 150 of the interference filter 100, and the light intensity of the passing component light is constant for each distance _lG of the gap G. Rotate the interference filter 100 so that That is, when the interference filter 100 is fixed so that the tilt angle of the interference filter 100 is constant as in the first embodiment, when the distance _lG of the gap G is changed, the first mirror 131 moves along the optical axis _LD . The overlapping area of the first hole portion 131A and the second hole portion 141A when projected onto the second mirror 141 changes. Therefore, every time the gap G is changed, the light amount of the passing component light slightly fluctuates. On the other hand, in the present embodiment, the angle at which the light amount of the passing component light does not change when the gap G is changed is measured in advance, and the angle of the interference filter 100 is set to the distance l _G of the gap G (optical path length Vary according to the difference l). As a result, even when the gap G is changed, the light quantity of the passing component light serving as a reference becomes constant, and the light intensity of the interference light can be measured appropriately.

[Effects of this embodiment]
The spectroscopic measurement apparatus 10A of the present embodiment includes an interference filter 100, a light detection section 12, and an angle adjustment section 14 that changes the installation angle of the interference filter 100 with respect to the optical axis _LD of the light detection section 12. Prepare.
Accordingly, as described above, even when the distance of the gap G is slightly changed by the electrostatic actuator 150, the installation angle of the interference filter 100 is adjusted by the angle adjuster 14 so that the light amount of the passing component light is constant. You can control it. Therefore, the spectroscopic measurement device 10A can perform spectroscopic measurement with higher accuracy.

[Modification]
In addition, the present invention is not limited to the above-described embodiments, and includes modifications, improvements, and configurations obtained by appropriately combining each embodiment within the scope of achieving the object of the present invention. It is.

[Modification 1]
In the first embodiment described above, as an example of the first mirror 131 and the second mirror 141, as shown in _FIG . An example in which the portion 131A and the second hole portion 141A are provided is shown.
On the other hand, the shapes of the first mirror 131 and the second mirror 141 are not limited to this. FIG. 7 is a diagram showing another configuration example of the first mirror.
For example, as shown in FIG. 7, as the first mirror 131, a plurality of first holes 131C arranged evenly along the X direction and the Y direction may be provided. Even in this case, as in the first embodiment, in the first mirror 131, the first hole 131C serves as the first passing portion, and the portion where the first hole 131C is not provided serves as the first reflecting portion 131B. Although the illustration of the second mirror 141 is omitted, it has the same shape as the first mirror 131 and is provided with a plurality of second holes evenly arranged along the X direction and the Y direction.
When applying the interference filter 100 having such a configuration to the spectrometer 10 , an image sensor having a plurality of pixels can be used as the photodetector 12 . That is, the interference filter 100 is arranged so that the passing component light that has passed through one first hole 131C and one second hole of the interference filter 100 is incident on one pixel of the photodetector 12 (image sensor). Deploy. This makes it possible to detect the change in light intensity for each pixel when the distance _lG of the gap G is changed, and to calculate the spectral spectrum for each pixel.

3, the first mirror 131 is provided with a plurality of slit-shaped first holes 131A along the Y direction, and in FIG. 7, the first mirror 131 is provided with a plurality of arrayed holes along the X and Y directions. Although the configuration in which the first hole portion 131C is provided is exemplified, a plurality of rectangular mirrors may be arranged. For example, a plurality of first mirrors that are long in the Y direction may be arranged in the X direction at intervals. Alternatively, the rectangular first mirrors may be arranged in an array at intervals along the X and Y directions. In these cases, the portion where the first mirror is not arranged becomes the first passing portion, and the portion where the first mirror is provided becomes the first reflecting portion. Note that the same applies to the second mirror 141 as well.

[Modification 2]
In the above-described first embodiment, the optical system 11 converts incident light into the spectrometer 10 into parallel light parallel to the optical axis _LD , and the filter center axis _LF is inclined with respect to the optical axis _LD . Although an example in which the parallel light is made incident on the interference filter 100, which is formed by the parallel light, the present invention is not limited to this.
8 and 9 are diagrams showing configuration examples in which the filter center axis _LF is parallel to the optical axis _LD of the photodetector 12. FIG.
For example, the spectroscopic measurement apparatus 10B in FIG. 8 has an optical system 11 (not shown) that expands the beam diameter of incident light, such as an aperture or a concave lens. 100 is injected. In this case, even if the interference filter 100 is not tilted, the passing component light that directly passes through the first hole 131A and the second hole 141A and the first hole 131A through the second reflecting portion 141B and the first reflecting portion 131B Interference light with the reflected component light that passes through the second hole 141A after being reflected can be obtained.

In addition, in the interference filter 100A of the spectrometer 10C shown in FIG. 9, the first optical region 130 of the first substrate 110 includes a plurality of planar portions 132 and an angle from the planar portion to the filter central axis _LF from 0 degrees. and a plurality of inclined portions 133 inclined at an inclination angle larger than 90 degrees.
Here, the plane portion 132, which is a plane parallel to the XY plane, serves as a first passing portion through which incident light from the first substrate 110 passes. On the other hand, each inclined portion 133 is provided with a first mirror 134 to constitute a first reflecting portion.
The same applies to the second optical region 140 of the second substrate 120. A plurality of flat portions 142 constituting the second passing portion and a plane portion 142 with respect to the filter center axis _LF are more than 0 degrees and more than 90 degrees. It includes a plurality of inclined portions 143 inclined at a small angle of inclination, and a second mirror 144 provided on each inclined portion 143 and constituting a second reflecting portion.
In addition, in the interference filter 100A shown in FIG. 9, an enlarged view is shown in which a part of the first optical region 130 and the second optical region 140 are enlarged in consideration of the visibility of the drawing. , is the same as the first embodiment.

In such an interference filter 100A, the filter central axis _LF is arranged so as to be parallel to the optical axis _LD of the light detection unit 12, and the same optical system 11 as in the first embodiment is used, The light collimated by the optical system 11 is made incident on the interference filter 100A. Accordingly, as in the first embodiment, it is possible to output interference light between the passing component light and the reflected component light from each second hole 141A.
In addition, in the example shown in FIG. 9, the inclined portion 133 protrudes from the first substrate 110 toward the second substrate 120, and the inclined portion 143 protrudes from the second substrate 120 toward the first substrate 110, but the present invention is not limited to this. . The inclined portion 133 may be formed in a concave shape from the mirror installation portion 112 of the first substrate 110 so that a portion of the inclined portion 133 is an inclined surface. Similarly, the inclined portion 143 may be formed in a concave shape from the surface facing the first substrate 110 of the movable portion 121 of the second substrate 120 so that a portion of the inclined portion 143 forms an inclined surface.

[Modification 3]
In the first embodiment, the first reflecting portion 131B of the first mirror 131 and the second reflecting portion 141B of the second mirror 141 do not transmit light but totally reflect the incident light. not. For example, the first mirror 131 and the second mirror 141 may be composed of a semi-transmissive semi-reflective optical thin film.
In this case, after passing through the first reflecting portion 131B, the passing component light passes through the second hole portion 141A or passes through the second reflecting portion 141B as it is. It also includes light that has entered the second reflecting portion 141B but has passed through the second reflecting portion 141B as it is. Similarly, the reflected component light passes through the first reflecting portion 131B, is reflected by the second reflecting portion 141B and the first reflecting portion 131B, and then passes through the second hole portion 141A or passes through the second reflecting portion 141B. The transmitted light passes through the first hole portion 131A, is reflected by the second reflecting portion 141B and the first reflecting portion 131B, and then enters the second reflecting portion 141B, but passes through the second reflecting portion 141B as it is. is also included.
However, in this case, as with a normal Fabry-Perot etalon, light components are multiple-reflected between the first reflecting portion 131B and the second reflecting portion 141B. may decrease. On the other hand, as in the above embodiment, the first reflecting portion 131B and the second reflecting portion 141B are configured to totally reflect the light, thereby reducing the measurement accuracy and simplifying the Fourier analysis. be able to.

[Modification 4]
In the first embodiment, the electrostatic actuator 150 was exemplified as the distance changer, but it is not limited to this.
For example, a configuration may be adopted in which a piezoelectric body is provided between the first substrate 110 and the second substrate 120 and expands and contracts according to the driving voltage. Alternatively, a closed space may be formed between the first substrate 110 and the second substrate 120, a pump may be connected to change the internal pressure of the closed space, and the distance of the gap G may be changed by changing the internal pressure.
Furthermore, as in the second embodiment, the angle adjusting section 14 that changes the installation angle of the interference filter 100 may function as a distance changing section. In other words, in the interference filter 100, although the distance _lG in the gap G is fixed, by changing the angle of the interference filter 100 with the angle adjusting section, the optical path length from the first reflecting section 131B to the second reflecting section 141B is can be changed.

[Modification 5]
In the above-described first embodiment, the movable portion 121 and the diaphragm portion 122 are provided on the second substrate 120 arranged on the side from which light is emitted. A configuration for advancing and retreating on the 120 side may be incorporated. For example, the first substrate 110 may be configured to have a movable portion and a diaphragm portion similar to those of the second substrate 120 .

[Summary of this disclosure]
The interference filter according to the first aspect of the present disclosure includes a first optical region and a second optical region facing each other across a gap, and a distance changer that changes the distance between the first optical region and the second optical region wherein the first optical region includes a first passing portion that transmits light and a first reflecting portion that reflects light, and the second optical region includes a second passing portion that transmits light and a second reflecting portion for reflecting light, the side opposite to the second optical region of the first optical region is the light incident side, and the side opposite to the first optical region of the second optical region is the light emission side, part of the incident light that enters from the light incidence side passes through the first passing section, is reflected in order by the second reflecting section and the first reflecting section, and The reflected component light passes through the second passing section, and the other portion passes through the first passing section and passes through the second passing section without being reflected by the second reflecting section and the first reflecting section. The reflected component light and the passing component light are emitted to the light emitting side.

In such an interference filter, since the light emitted from the interference filter includes the passing component light, the light intensity of the emitted light can be increased compared to, for example, a Fabry-Perot etalon.

The interference filter of the first aspect comprises a first substrate having the first optical region and a second substrate having the second optical region, wherein the first optical region is the second optical region of the first substrate. provided on a surface facing the substrate and having a plurality of first holes forming the first passing portion, and a portion other than the first hole portions being constituted by a first mirror forming the first reflecting portion; , the second optical region is provided on a surface of the second substrate facing the first substrate, has a plurality of second holes constituting the second passing portion, and has a plurality of second holes other than the second holes A portion is composed of a second mirror that constitutes the second reflecting portion.

Accordingly, by providing a first mirror having a plurality of first holes for the first substrate and providing a second mirror having a plurality of second holes for the second substrate, the above-described , an interference filter that emits interference light between the passing component light and the reflected component light can be easily configured.

In the interference filter of the first aspect, when the first optical region is projected onto the second optical region in the direction in which the incident light travels, the first passing section includes a part of the second passing section and the It overlaps a portion of the second reflecting portion, and the second passing portion overlaps a portion of the first passing portion and a portion of the first reflecting portion.
As a result, incident light from one direction (the traveling direction of the incident light) is converted into parallel light and made incident on the interference filter, so that in the entire region where the first optical region and the second optical region overlap with respect to the traveling direction, Interference light between the passing component light and the reflected component light can be emitted from each second passing portion included in the .

A spectroscopic measurement device according to a second aspect of the present disclosure includes the interference filter according to the first aspect described above, and a light detection section that detects light emitted from the light emission side of the interference filter.
As described above, the interference filter of the first aspect can increase the intensity of emitted light compared to, for example, a Fabry-Perot etalon. Therefore, in a spectrometer using the interference filter, the amount of light received by the photodetector can be increased when the photodetector detects light emitted from the interference filter. This makes it possible to perform spectroscopic measurement with reduced influence of noise.

The spectroscopic measurement device of the second aspect further includes an angle adjustment section that changes the installation angle of the interference filter with respect to the optical axis of the light detection section.
When the distance between the first optical region and the second optical region is changed by the distance changer, the light amount of the passing component light is slightly changed. In contrast, in this aspect, the installation angle of the interference filter can be changed by the angle adjustment section, and the installation angle of the interference filter can be changed according to the distance between the first optical region and the second optical region. can be done. This makes it possible to measure the change in the light intensity of the interference light when the distance between the first optical region and the second optical region is changed while the light intensity of the passing component light is kept constant.

A spectroscopic measurement system according to a third aspect of the present disclosure includes a spectroscopic measurement device according to the second aspect, and based on a signal value output from the photodetector, the light intensity of light of each wavelength included in the incident light is determined. a calculating processor, wherein the processor calculates the light intensity of the light of each wavelength from the change in the signal value when the gap is changed by Fourier analysis.
In this aspect, the spectrometer can measure the light intensity of interference light between the transmitted component light and the reflected component light when the distance between the first optical region and the second optical region of the interference filter is changed. The interference light is synthesized light in which a plurality of lights of specific wavelengths λ that satisfy l=nλ are strengthened according to the optical path length difference l between the transmitted component light and the reflected component light. Therefore, by measuring the light intensity of the interference light by changing the optical path difference l and performing Fourier analysis, it is possible to calculate the light intensity for each wavelength λ, that is, the spectral spectrum of the incident light with high accuracy. can.

DESCRIPTION OF SYMBOLS 1... Spectroscopic measurement system 10, 10A, 10B, 10C... Spectroscopic measuring apparatus 11... Optical system 12... Photodetection part 13... Module control part 14... Angle adjustment part 14A... Holding part 14B... Rotation Drive shaft 20 Control device 21 Storage unit 22 Processor 100, 100A Interference filter 110 First substrate 111 Electrode arrangement groove 112 Mirror installation unit 120 Second substrate 121 Movable part 122... Diaphragm part 123... Substrate outer peripheral part 130... First optical area 131, 134... First mirror 131A, 131C... First hole (first passing part) 131B... First reflecting part , 140... Second optical region 141, 144... Second mirror 141A... Second hole (second passage part) 141B... Second reflection part 150... Electrostatic actuator (distance changing part) 151... Second One electrode 152 Second electrode 221 Measurement command unit 222 Analysis unit G Gap _LD Optical axis of photodetector _LF Filter central axis W Measurement target.

Claims (6)

a first optical region and a second optical region facing each other across a gap;
a distance changing unit that changes the distance between the first optical region and the second optical region,
The first optical region includes a first passing portion for passing light and a first reflecting portion for reflecting light,
The second optical region includes a second passing portion for passing light and a second reflecting portion for reflecting light,
When the side of the first optical region opposite to the second optical region is the light incident side, and the side of the second optical region opposite to the first optical region is the light exiting side, from the light incident side A portion of the incident light that is incident passes through the first passing portion, is reflected in turn by the second reflecting portion and the first reflecting portion, becomes reflected component light that passes through the second passing portion, and becomes other A part of the light passes through the first passing section and becomes the passing component light that passes through the second passing section without being reflected by the second reflecting section and the first reflecting section, and the reflected component light and the passing component an interference filter through which light is emitted to the light exit side. a first substrate having the first optical region;
a second substrate having the second optical region,
The first optical region is provided on a surface of the first substrate facing the second substrate, and has a plurality of first holes that constitute the first passing portion, and a portion other than the first holes. is composed of a first mirror that constitutes the first reflecting section,
The second optical region is provided on a surface of the second substrate facing the first substrate, has a plurality of second holes that constitute the second passing portion, and has portions other than the second holes. is composed of a second mirror that constitutes the second reflecting section,
2. An interference filter as claimed in claim 1. When the first optical region is projected onto the second optical region in the direction of travel of the incident light, the first passing portion is a part of the second passing portion and a part of the second reflecting portion. overlapping, wherein the second passing portion overlaps a portion of the first passing portion and a portion of the first reflecting portion;
3. An interference filter according to claim 1 or claim 2. an interference filter according to any one of claims 1 to 3;
a photodetector that detects light emitted from the light emission side of the interference filter;
A spectrometer, comprising: Further comprising an angle adjustment unit that changes the installation angle of the interference filter with respect to the optical axis of the light detection unit,
The spectroscopic measurement device according to claim 4. A spectroscopic measurement device according to claim 4 or claim 5;
a processor that calculates the light intensity of light of each wavelength included in the incident light based on the signal value output from the light detection unit;
The processor calculates the light intensity of the light of each wavelength from the change in the signal value when the gap is changed by Fourier analysis.
Spectroscopic measurement system.

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